The mining industry frequently utilizes mills (e.g., rotary mills, ball mills, rod mills, semiautogenous mills, autogenous mills, etc.) to reduce the size of masses of material structures (e.g., ore) mined from the earthen formations. During use and operation of a mill, mined structures (and, optionally, other structures, such as balls, rods, etc.) are typically lifted and dropped back onto other mined structures to form relatively smaller structures through the resulting impacts. The process can be continuous, with relatively large mined material structures being delivered into one end of the mill and relatively smaller material structures (e.g., particles) of the mined material exiting an opposite end of the mill.
Generally, internal surfaces of a mill are covered (e.g., lined) with wear-resistant structures (e.g., liners, plates, etc.) sized and shaped to prevent damage to the mill resulting from contact between the mined material structures (and, optionally, other structures) and the internal surfaces of the mill during use and operation of the mill. The mined material structures contact and degrade (e.g., wear, abrade, etc.) the wear-resistant structures rather than the internal surfaces of the mill. The wear-resistant structures may be attached to the internal surfaces of the mill by way of retaining structures (e.g., retaining bolts), and may be detached and replaced upon exhibiting significant wear. Thus, the wear-resistant structures can prolong the durability and use of the mill.
A mill is typically configured to accommodate a variety of wear-resistant structure configurations (e.g., shapes, sizes, retaining structure hole distributions, retaining structure hole sizes, retaining structure hole shapes, etc.). For example, a shell of a conventional mill can include a variety of openings (e.g., holes, apertures, vias, etc.) independently configured (e.g., sized and shaped) and positioned to accommodate different shapes, sizes, and distributions of wear-resistant structures and retaining bolts. Depending on the configurations and positions of the wear-resistant structures and the retaining structures, some of the holes may be filled with the retaining structures while other of the holes may be free of (e.g., unfilled by) the retaining structures. Deformable plug structures (e.g., cork plugs, rubber plugs, etc.) may be provided within the holes free of the retaining bolts to prevent materials (e.g., corrosive fluids) within the mill from escaping during use and operation of the mill. Such deformable plug structures are generally wedged into upper portions of the holes (e.g., portions of the holes proximate external surfaces of the mill opposite internal surfaces of the mill), and are retained therein until the wear-resistant structures require replacement.
Unfortunately, the configurations and positions of conventional deformable plug structures can create problems for milling operations. For example, conventional deformable plug structures can be difficult to extract (e.g., pry, pull, etc.) from the holes in the mill shell, requiring excessive amounts of time and labor. Such excessive amounts of time and labor can reduce the efficiency and throughput of milling operations by undesirably prolonging wear-resistant structure replacement operations. In addition, conventional deformable plug structures may be nearly impossible to remove without sustaining significant damage thereto, preventing reuse of conventional deformable plug structures for subsequent milling operations. Furthermore, the materials (e.g., cork, rubber, etc.) of conventional deformable plug structures can degrade (e.g., deteriorate, decompose, break down, etc.) under the environmental conditions (e.g., temperatures; pressures; materials, such as solvents, corrosive liquids, lubricants, small particles, etc.; rotational speeds; etc.) present in conventional milling operations, which can decrease process safety and/or result in one or more of equipment damage and undesirable maintenance downtime.
It would, therefore, be desirable to have new assemblies, plug devices, and methods for milling operations that reduce, if not eliminate, at least some of the aforementioned problems.